The present disclosure relates in general to host devices, such as portable media devices, that can interoperate with accessories, and in particular to interoperation of a host device with an accessory via multiple communication paths.
A portable media device generally refers to a handheld device that is capable of managing and/or playing back media assets such as audio, video, and still image files. Some portable media devices, such as the iPod®, iPhone®, and iPad® available from Apple Inc. of Cupertino, Calif., can provide users a variety of services in addition to media management and playback. Examples of such services include the storage of personal data such as calendar, contacts, and notes; Internet access; mobile telephony; and the ability to selectively download and run various application programs.
A portable media device typically includes a number of connectors or ports that can be used to interface with other devices. For instance, one connector or port can be used to establish a connection between the portable media device and a host computer for transferring data to/from the host computer. Another (or the same) connector or port can be used to establish a connection between the portable media device and an accessory device (referred to herein as an accessory) for, e.g., playing back or presenting media assets stored on the portable media device.
Some accessories are capable of interfacing with a portable media device via multiple connectors or ports of the portable media device. These accessories can be composed of a single physical device, or a number of separate physical devices that are designed to be components of a single logical device. For example, an accessory can be composed of a car head unit and a hands-free headset that are designed to be part of a single audio system. The car head unit can be capable of interfacing with a portable media device via a wired connection (e.g., 30-pin serial, USB, etc.) as well as via a wireless connection (e.g., Bluetooth). At the same time, the hands-free headset can be capable of interfacing with the portable media device via another wireless connection.
In situations such as the foregoing where an accessory can potentially interface with a portable media device via many connections, there is no protocol for informing the portable media device that the various connections to the accessory are associated (i.e., all route to the same logical accessory). The portable media device assumes that each connection (and each communication path in the connection) is separate and independent of any other. As a result, the portable media device cannot interoperate with the accessory to perform routing of information over the multiple connections/communication paths.